Initial closed operation of the CELSS Test Facility Engineering Development Unit.

As part of the NASA Advanced Life Support Flight Program, a Controlled Ecological Life Support System (CELSS) Test Facility Engineering Development Unit has been constructed and is undergoing initial operational testing at NASA Ames Research Center. The Engineering Development Unit (EDU) is a tightly closed, stringently controlled, ground-based testbed which provides a broad range of environmental conditions under which a variety of CELSS higher plant crops can be grown. Although the EDU was developed primarily to provide near-term engineering data and a realistic determination of the subsystem and system requirements necessary for the fabrication of a comparable flight unit, the EDU has also provided a means to evaluate plant crop productivity and physiology under controlled conditions. This paper describes the initial closed operational testing of the EDU, with emphasis on the hardware performance capabilities. Measured performance data during a 28-day closed operation period are compared with the specified functional requirements, and an example of inferring crop growth parameters from the test data is presented. Plans for future science and technology testing are also discussed.

In-situ resource utilization technologies for Mars life support systems.

The atmosphere of Mars has many of the ingredients that can be used to support human exploration missions. It can be "mined" and processed to produce oxygen, buffer gas, and water, resulting in significant savings on mission costs. The use of local materials, called ISRU (for in-situ resource utilization), is clearly an essential strategy for a long-term human presence on Mars from the standpoints of self-sufficiency, safety, and cost. Currently a substantial effort is underway by NASA to develop technologies and designs of chemical plants to make propellants from the Martian atmosphere. Consumables for life support, such as oxygen and water, will probably benefit greatly from this ISRU technology development for propellant production. However, the buffer gas needed to dilute oxygen for breathing is not a product of a propellant production plant. The buffer gas needs on each human Mars mission will probably be in the order of metric tons, primarily due to losses during airlock activity. Buffer gas can be separated, compressed, and purified from the Mars atmosphere. This paper discusses the buffer gas needs for a human mission to Mars and consider architectures for the generation of buffer gas including an option that integrates it to the propellant production plant.

Recent advances in technologies required for a "Salad Machine".

Future long duration, manned space flight missions will require life support systems that minimize resupply requirements and ultimately approach self-sufficiency in space. Bioregenerative life support systems are a promising approach, but they are far from mature. Early in the development of the NASA Controlled Ecological Life Support System Program, the idea of onboard cultivation of salad-type vegetables for crew consumption was proposed as a first step away from the total reliance on resupply for food in space. Since that time, significant advances in space-based plant growth hardware have occurred, and considerable flight experience has been gained. This paper revisits the "Salad Machine" concept and describes recent developments in subsystem technologies for both plant root and shoot environments that are directly relevant to the development of such a facility.

Approaches in the determination of plant nutrient uptake and distribution in space flight conditions.

The effective growth and development of vascular plants rely on the adequate availability of water and nutrients. Inefficiency in either the initial absorption, transportation, or distribution of these elements are factors which impinge on plant structure and metabolic integrity. The potential effect of space flight and microgravity conditions on the efficiency of these processes is unclear. Limitations in the available quantity of space-grown plant material and the sensitivity of routine analytical techniques have made an evaluation of these processes impractical. However, the recent introduction of new plant cultivating methodologies supporting the application of radionuclide elements and subsequent autoradiography techniques provides a highly sensitive investigative approach amenable to space flight studies. Experiments involving the use of gel based 'nutrient packs' and the radionuclides calcium-45 and iron-59 were conducted on the Shuttle mission STS-94. Uptake rates of the radionuclides between ground and flight plant material appeared comparable.

Controlled Ecological Life Support Systems (CELSS) flight experimentation.

The NASA CELSS program has the goal of developing life support systems for humans in space based on the use of higher plants. The program has supported research at universities with a primary focus of increasing the productivity of candidate crop plants. To understand the effects of the space environment on plant productivity, the CELSS Test Facility (CTF) has been been conceived as an instrument that will permit the evaluation of plant productivity on Space Station Freedom. The CTF will maintain specific environmental conditions and collect data on gas exchange rates and biomass accumulation over the growth period of several crop plants grown sequentially from seed to harvest. The science requirements of the CTF will be described, as will current design concepts and specific technology requirements for operation in micro-gravity.

Life support systems for Mars transit.

The long-held human dream of travel to the stars and planets will probably be realized within the next quarter century. Preliminary analyses by U.S. scientists and engineers suggests that a first trip to Mars could begin as early as 2016. A proposal by U.S.S.R. space planners has suggested that an effort involving the cooperation and collaboration of many nations could begin by 2011. Among the major considerations that must be made in preparation for such an excursion are solidification of the scientific, economic and philosophical rationales for such a trip made by humans, and realistic evaluations of current and projected technical capabilities. Issues in the latter category include launch and propulsion systems, long term system stability and reliability, the psychological and physiological consequences of long term exposure to the space environment, the development and use of countermeasures to deleterious human physiological responses to the space environment, and life support systems that are both capable of the immense journey and reliable enough to assure their continued operation for the duration of the voyage. Many of the issues important in the design of a life support system for a Mars trip are based on reasonably well understood data: the human requirements for food, oxygen and water. However, other issues are less well-defined, such as the demands that will be made on the system for personal cleanliness and hygiene, environmental cleanliness, prevention or reduction of environmental toxins, and psychological responses to the environment and to the diet. It is much too early to make final decisions about the characteristics of the long-duration life support system needed for travel to Mars, or for use on its surface. However, it is clear that life support systems will evolve during the next few decades form the relatively straightforward systems that are used on Shuttle and Soyuz, to increasingly more complex and regenerative systems. The Soviet Union has an operating life support system on Mir that can apparently evolve, and the United States is currently planning the one for Space Station Freedom that will use partial regeneration. It is essential to develop concepts now for life support systems on an advanced Space Station, the lunar outpost (to be launched in about 2004) and the lunar base. Such concepts will build on current technology and capabilities. But because of the variety of different technologies that can be developed, and the potential for coordinating the functions of very diverse sub-systems within the same life support system, the possibility of developing an efficient, reliable mixed process system is high. It is likely that a life support system for Mars transit and base will use a composite of physical, chemical, and biological processes. The purpose of this paper is to explore the potentially useful structural elements of a life support system for use on a Mars trip, and to identify the features that, at this time, appear to be most appropriate for inclusion in the system.